U.S. patent number 4,147,833 [Application Number 05/852,116] was granted by the patent office on 1979-04-03 for glass fiber coating composition.
This patent grant is currently assigned to PPG Industries, Inc.. Invention is credited to George E. Eilerman, Albert E. Tamosauskas.
United States Patent |
4,147,833 |
Eilerman , et al. |
April 3, 1979 |
Glass fiber coating composition
Abstract
Individual glass fibers are coated with a composition which
includes the condensation product of a polycarboxylic acid or
anhydride and a polyfunctional amine. The preferred coating
composition, comprises an aqueous mixture including the
aforementioned condensation product and an elastomeric
styrene-butadiene-vinylpyridine terpolymer latex. An aqueous
solution of the coating composition is prepared and applied to
glass fibers as a sizing composition and/or as a coating
composition after the glass fibers are sized. Subsequent to coating
the glass fiber strands with the aforementioned coating
composition, the strands are dried by heating in a microwave oven,
a forced air oven or the like.
Inventors: |
Eilerman; George E.
(Pittsburgh, PA), Tamosauskas; Albert E. (Pittsburgh,
PA) |
Assignee: |
PPG Industries, Inc.
(Pittsburgh, PA)
|
Family
ID: |
25180380 |
Appl.
No.: |
05/852,116 |
Filed: |
November 16, 1977 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
801171 |
May 27, 1977 |
4074988 |
|
|
|
637341 |
Dec 3, 1975 |
|
|
|
|
512648 |
Oct 7, 1974 |
|
|
|
|
384876 |
Aug 2, 1973 |
|
|
|
|
Current U.S.
Class: |
428/378; 428/375;
428/435; 524/262; 524/514; 65/451 |
Current CPC
Class: |
C03C
25/1015 (20130101); C08J 5/08 (20130101); Y10T
428/2938 (20150115); Y10T 428/31623 (20150401); Y10T
428/2933 (20150115); C08J 2321/00 (20130101) |
Current International
Class: |
C03C
25/10 (20060101); C08J 5/04 (20060101); C08J
5/08 (20060101); C08L 007/00 () |
Field of
Search: |
;428/397,378 ;65/3
;260/23,29.2N,856,29.7T,29.7UA,29.7NR |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lesmes; George F.
Assistant Examiner: Buffalow; E. Rollins
Attorney, Agent or Firm: Stachel; Kenneth J. McDonald; Alan
T.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a division of application Ser. No. 801,171,
filed May 27, 1977, now U.S. Pat. No. 4,074,988 which is a
continuation of application Ser. No. 637,341, filed Dec. 3, 1975,
now abandoned, which is a continuation of application Ser. No.
512,648, filed Oct. 7, 1974, now abandoned, which is a
continuation-in-part of application Ser. No. 384,876, filed Aug. 2,
1973, now abandoned.
Claims
We claim:
1. A composition for coating glass fibers for use in reinforcing
elastomeric materials consisting essentially of:
a. water and ammonium hydroxide: 60 to 85 percent by weight;
b. an elastomeric latex: 20 to 70 percent by weight;
c. a condensation reaction product of
i. a polycarboxylic acid;
ii. an anhydride;
iii. a polyanhydride; or
iv. a tricarboxylic monoanhydride and
a polyfunctional amine: 3 to 15 percent by weight; said reaction
product being soluble is aqueous ammonia.
2. The coating composition of claim 1 in which said composition is
a combined sizing and coating composition and includes up to 5
percent by weight of an amino silane.
3. The coating composition of claim 1 in which said composition is
a combined sizing and coating composition and includes up to 5
percent by weight of a uredo silane.
4. The coating composition of claim 1 wherein said elastomeric
latex is styrene-butadiene-vinyl pyridine latex.
5. Glass fibers having thereon the dried residue of the coating
composition of claim 1.
Description
BACKGROUND OF THE INVENTION
This invention relates to coating compositions for glass fibers and
more particularly to an aqueous coating composition that includes
the condensation product of a polycarboxylic acid or anhydride and
a polyfunctional amine for coating glass fibers for use in
reinforcing elastomeric products.
It has long been recognized that glass fibers should make an ideal
reinforcement for automobile tires (U.S. Pat. No. 2,184,326),
rubber timing belts (U.S. Pat. No. 2,135,057) and other rubber or
rubberlike materials. In preparing glass fibers for such
applications, glass fibers in the form of strands, yarn, roving or
fabric are coated with an adhesive to aid in bonding of the glass
to elastomeric material. By far the most widely used adhesive for
preparing glass fibers for reinforcing rubber or rubberlike
materials is a resorcinol-formaldehyde resin with an elastomeric
latex. The resorcinol-formaldehyde resin is generally applied to
glass fiber material prior to molding of the reinforced article by
contacting a glass fabric, strand, yarn or the like with an aqueous
latex mixture having the resorcinol-formaldehyde resin dispersed
therein. Largely because of its high cost a satisfactory substitute
for all or part of the resorcinol-formaldehyde resin has long been
sought. Additionally the resorcinol-formaldehyde resin latex
mixture is difficult to apply to glass fabric in a manner whereby
the resin may thoroughly impregnate and coat the glass fibers which
form the fabric. Therefore uncoated glass fiber strands often times
remain in the fabric after being contacted with the resinous
mixture. These strands are subject to glass on glass abrasion which
soon destroys the long strands of glass and renders its reinforcing
properties unsatisfactory. Further, resorcinol-formaldehyde resins
in aqueous solution, over a long period of time, and when subjected
to both ambient and superambient temperatures, have a tendency to
further polymerize thereby changing the chemical and physical
properties of the coatings formed therefrom.
It has been proposed that glass fiber materials be coated while
being formed with a rubber adhesive in order to insure complete
coating of a glass fiber with coating materials. For example, a
glass fiber strand composed of a multitude of individual fine glass
fibers or filaments formed by being drawn from a molten cone of
glass located at the tips of small orifices in a bushing such as
shown in U.S. Pat. No. 2,133,238 are contacted with a bath
containing the adhesive material. However, difficulty has been
encountered in coating glass fibers in this manner because the
adhesive resorcinol-formaldehyde latex mixture remains tacky after
application and drying and interferes with subsequent twisting,
winding and spinning operations performed on the glass fibers to
form roving, yarn, fabric and the like.
In a typical two-step operation glass fibers formed as described
above are coated while moving at a high speed with the sizing
composition containing a glass binder and lubricant to yield a
strand comprising a multitude of individual glass filaments having
sufficient integrity for workability in formation into yarn or the
like. After the size has been applied to the glass, a number of
strands in parallel form are coated with the coating composition,
dried and then wound on a tubular support to form glass fiber
roving which may then be formed by twisting, spinning or weaving
into yarn fabric or other forms suitable for use as reinforcement
for elastomeric products.
By sizing composition, as opposed to a coating composition, is
meant a composition for coating glass fibers useful for reinforcing
rubber and rubberlike materials characterized by a weight gain of
glass fiber material when subject to a sizing treatment of about
0.5 to 2 percent based upon dry glass as opposed to a weight gain
of about 15 to 40 percent based upon dry glass in a coating
application wherein a rubber adhesive is applied to the glass fiber
material.
A sizing composition or size is usually an aqueous dispersion
including the addition of a lubricant, a coupling agent or finished
material. The coupling agent or finished material renders the
surface of the glass fibers compatible with the resin with which
they are to be employed in preparing a glass fiber reinforced
elastomeric product and aids in bonding the fibers thereto.
U.S. Pat. No. 3,718,448 entitled "Fiber Forming and Coating
Process" by Warren W. Drummond and Donald W. Denniston assigned to
the assignee of this invention discloses apparatus for applying a
combined sizing and coating composition to individual glass fibers
and then drying the fibers in strands and collecting the dried
strands on a forming tube. By this process the glass fibers are
simultaneously coated with both the sizing and coating in a single
coating step that reduces substantially the time and equipment
required to process the glass fibers for use as a reinforcement in
elastomeric products. The combined sizing and coating composition
previously employed with this process included only
resorcinol-formaldehyde as the resin constituent. There is a need
therefore for a coating composition and/or a combined sizing and
coating composition that may be more economically prepared and
applied to the glass fibers and has increased stability over the
conventional resorcinol-formaldehyde based adhesive
compositions.
SUMMARY OF THE INVENTION
This invention provides novel coating compositions for preparing
glass fibers for use in reinforcing elastomeric products. The
invention provides novel coating compositions for glass fibers
permitting improved impregnation of a glass fiber strand composed
of a multiplicity of individual glass filaments with rubber
adhesive. Additionally there are provided combined sizing and
coating compositions for glass fibers enabling the application of
sizing and adhesive chemicals to a glass fiber strand in a
single-step application.
The invention provides a coating composition for glass fibers for
use in reinforcing elastomeric products wherein the condensation
product of a polycarboxylic acid, or an anhydride or a
polyanhydride, and a polyfunctional amine is a major constituent. A
typical combined sizing and coating composition comprises an
aqueous mixture of the abovementioned condensation product and an
elastomeric latex particular styrene-butadiene-vinylpyridine
terpolymer rubber latex. The rubber adhesive portion of the coating
composition comprises generally the polycarboxylic acid or
anhydride or polyanhydride-polyfunctional amine condensation
product which is soluble in aqueous ammonia. This condensation
product may be employed in admixture with the remaining ingredients
to form a material useful for both sizing and coating glass fibers
in a single application as the glass fibers are formed and drawn.
The procedure involving both the sizing and coating procedures in a
single step is more fully disclosed in U.S. Pat. No. 3,718,449.
Alternatively the rubber adhesive portion together with the latex
portion may be applied to a previously sized glass fiber in the
form of strands or yarns in a subsequent application step.
In addition to the rubber adhesive and latex composition described
above, a silicone coupling agent may be employed to aid in the
bonding of the adhesive composition to the glass fibers. Preferably
the coupling agent is an amino silane type coupling agent having
the general formula: ##STR1## or a uredo silane coupling agent
having the general formula: ##STR2## wherein R.sub.1, R.sub.2 and
R.sub.3 are the same or different and are selected from the lower
alkyl or aliphatic monovalent hydrocarbon radicals having less than
8 and more preferably less than 5 carbon atoms. R.sub.4 is a
divalent alkylene radical having less than 8 carbon atoms, and Z is
either 1 or 0. The coating composition and/or the combined sizing
and coating composition is employed at a level of about 15 to 40
percent by weight of the dried residue of the coating composition
as a weight gain on the initial glass fibers.
The following example is illustrative of a coating composition
and/or combined sizing and coating composition according to the
invention which may be used in the coating procedure more fully
described in U.S. Pat. No. 3,718,449 (the single-step process) for
applying the coating and sizing ingredients to the glass fiber
materials for preparing glass fibers for reinforcing elastomeric
products. Glass fibers may be contacted with the coating
composition as a combined sizing and coating composition as they
are formed. Preferably the glass fibers are contacted with a
composition within a few feet of the bushing and cone from which
they are being drawn as previously referred to in U.S. Pat. No.
3,718,449. The combined sizing and coating composition described
hereinafter and other compositions of the invention may also be
applied by conventional roller applicators such as described in
U.S. Pat. No. 2,873,718 or in the case of previously sized glass
fibers may be coated by applying the rubber adhesive composition by
means of passing the sized glass fiber strands over a plurality of
roller applicators placed in a bath of the aqueous coating
composition. Drying of the coated glass fibers may be accomplished
by passing the coated strands through a microwave oven, a forced
hot air oven or through other means which impart sufficient heat to
remove the water contained in the coating composition and promote
the reaction of the constituents therein to effect the partial or
complete cure.
A suitable formulation for the coating composition may be prepared
containing the following ranges of constituents:
______________________________________ Constituents Percent by
Weight ______________________________________ Polycarboxylic acid
or anhydride 3 to 15 and polyfunctional amine con- densation
product Styrene-Butadiene-vinylpyridine 20 to 70 rubber latex
(40-60% solids) Coupling agent 0 to 5 Water and ammonium hydroxide
60 to 85 ______________________________________
Although the exact structure of the condensation product is not
known, it is hypothesized that this condensation product is an
amide having pendant carboxyl groups. The extent of condensation is
such that a low molecular weight polyamide (less than a molecular
weight of 8,000) having pendant carboxyl groups which render the
polymer soluble in aqueous ammonia. The procedure for synthesizing
the condensation product of the polycarboxylic acid or anhydride
and the polyfunctional amine is as follows:
The polycarboxylic acid or anhydride and an alcohol solvent are
charged to an appropriately sized flask equipped with a heating
mantle, a reflux condenser, a thermometer, a stirrer, an addition
funnel, and a Dean and Star trap and stirred until homogeneous. The
polyfunctional amine is then added, by means of the addition
funnel, dropwise over about 2 hours while the temperature is being
raised by means of the heating mantle to the refluxing temperature
of the solution. After all the polyfunctional amine has been added,
the solution is then continually heated while the alcohol solvent
is removed by distillation. During the removal of the alcohol
solvent the temperature of the reaction mixture is constantly
rising due to the removal of the volatile alcohol solvent. After
about 2 hours of distillation a substantial amount of the alcohol
solvent is removed, and the reaction mixture is withdrawn from the
heat. At this time concentrated ammonium hydroxide solution (28
percent) is added to the reaction mixture to reduce the viscosity
to a desired level.
The condensation product is then prepared to be incorporated into a
coating or combined sizing and coating composition.
Typical anhydrides useful in producing the condensation product are
maleic anhydride, maleic anhydride copolymers and interpolymers,
succinic anhydride, phthalic anhydride, chlorenic anhydride,
tetrachlorophthalic anhydride and the like. Typical polycarboxylic
acids useful in producing the condensation product are citric acid,
oxydiethanoic acid, terephthalic acid, adipic acid, sebasic acid,
azaleic acid, hydrolyzed maleic acid copolymers and interpolymeers
and the like. A typical tricarboxylic monoanhydride useful in
producing the condensation product is trimellitic anhydride.
Typical polyfunctional amines useful in producing the condensation
product are diethylene triamine, di(triethylene) tetramine,
tetraethylene pentamine, propylene diamine, ethylene diamine, bis(2
aminoethyl) sulfide, poly(oxyethylene) diamine, polymers of
ethylenamine and the like.
Typical alcohols useful as solvents for the condensation reaction
are methanol, ethanol, isopropanol, butanol, isobutanol and the
like.
EXAMPLE I
Anhydride Polyfunctional Amine Reaction Product
To a 1 liter flask equipped with a mechanical stirrer, thermometer,
an addition funnel, a reflux condenser, a variable heating mantle
and a Dean and Stark trap is charged 294 grams of maleic anhydride
and 400 grams of isopropanol. This mixture is heated at reflux
until homogeneous at which time 238 grams of tetraethylene
pentamine is added dropwise by means of a dropping funnel over a
period of 1 hour and 20 minutes while maintaining the temperature
of the solution at about 90.degree. C. During the addition of the
amine, the solution changed colors from tannish yellow at the
beginning of the addition to dark brown at the end of the addition.
After all of the polyamine was added, increased heat was applied to
the reaction mixture and the isopropanol removed by distillation
was begun. After 31/2 hours of distillation 371 milliliters of
distillate consisting of isopropanol and water were removed. At
this time the pot temperature was 169.degree. C. 120 grams of
concentrated ammonium hydroxide solution (28 percent) mixed with
220 grams of water were added to the mixture after the agitation
was stopped and the heating mantle was removed from the flask. Upon
the addition of the above aqueous ammonia solution, the reaction
mixture rapidly cooled. After this initial ammonium hydroxide water
solution was added, an additional 25 grams of concentrated ammonium
hydroxide and 110 grams of water was added to reduce the viscosity
of the resin solution.
Coating Composition
The coating composition was prepared by mixing 30 grams of the
aforementioned condensation product, 138 grams of water and 0.5
gram of ammonium persulfate until homogeneous. At which time 75
grams of styrene-butadiene-2-vinylpyridine latex (41 percent
solids) was added to the coating mixture. It was noted that the
compatibility of the latex was excellent in the condensation
product mixture.
A sample of sized glass fiber yarn having 5 strands with a filament
count of 75 was dipped in the above coating composition. The coated
glass fiber yarn was cured in a 5 foot long muffle furnace at
450.degree. F. at 5 feet per minute and impregnated with standard
rubber stock used for producing tires. Typical commercial rubber
compounds containing principally styrene-butadiene rubber and
selected to have the following properties are used to test glass
fiber properties: optimum cure at 300.degree. F. about 30 minutes,
300 percent modulus at about 1900 pounds per square inch, tensile
strength of about 2900 pounds per square inch, elongation at
failure about 1.13.
The stripped adhesion for the coated glass fiber cord is determined
by the following method.
A cylindrical drum was wrapped with a 4 inch by 101/2 inch 40 mil
thick strip of rubber stock; the rubber stock occupied
substantially all the surface area of the cylindrical drum. The
coated glass fiber yarn is wrapped about the rubber stock on the
drum in a cylindrical fashion providing a continuous layer of yarn
over the rubber stock. The wound rubber stock is removed from the
cylinder and cut into a 3 inch by 10 inch sample.
A strip of 3 inch by 10 inch rubber is placed in a 3 inch by 10
inch mold and the above rubber strip with the coated strand thereon
is placed in the mold with the strand side away from the first
rubber strip. Two 3 inch by 1 inch strips of Holland cloth are
placed at opposite ends of the strand side of the rubber strip.
Another 3 inch by 10 inch rubber strip is placed over the Holland
cloth and lastly a 3 inch by 10 inch rubber strip with coated
strand thereon is placed on the last mentioned rubber strip with
the strand side in contact with the said last mentioned rubber
strip. The mold is closed and the rubber cord laminate is cured at
100 psi for 30 minutes at 300.degree. F. The rubber cord laminate
is removed from the mold and allowed to slowly cool overnight.
The laminate is cut into 51/2 inch by 1 inch strips and heated for
30 minutes at 230.degree. F. after which the Holland cloth is
removed from the laminate. After setting an Instron test device for
a gauge length of 1/2 inch to 3/4 inch and callibrating the unit
for a crosshead speed of 2 inches per minute, the bottom layer of
the heated rubber and exposed cord are placed in the top jaw, and
the top layer of the heated rubber in the bottom jaw of the test
device. The Instron test device is operated until a separation of 2
inches is obtained and the loading is noted. The top layer of
rubber is then inserted in the top jaw and the cord in the bottom
jaw with a gauge length of 1/2 to 3/4 inch. The Instron device is
again operated until a separaion of 2 inches is obtained and the
loading is noted. The test is repeated for the opposite end of the
specimen and for additional specimens included in the sample. The
results of the test are averaged for the adhesion of the cord to
rubber. Adhesion tested in this manner on several samples ranged
from 36 to 50 pounds.
EXAMPLE II
"E" glass composed of 54.4 percent by weight of SiO.sub.2, 13.4
percent by weight of Al.sub.2 O.sub.3, 21.7 percent by weight of
CaO, 0.4 percent by weight of MgO, 8.5 percent by weight of B.sub.2
O.sub.3, 0.5 percent by weight of F.sub.2, 0.7 percent by weight of
Na.sub.2 O, 0.5 percent by weight of TiO.sub.2, and 0.2 percent by
weight of Fe.sub.2 O.sub.3 is melted at 2400.degree. F. in an 80
percent platinum, 20 percent rhodium bushing containing orifices of
80 one thousandths of one inch in diameter. Glass fibers are then
drawn by attenuating the molten glass from cones of glass at the
bushing orifice to form glass fiber filaments. After the filaments
are formed, they are passed over a roller applicator having on the
surface thereof the coating composition (not a sizing composition)
of Example I. After the sizing composition is applied, the sized
filaments are gathered by means of a gathering shoe, into a strand.
The strand is then passed over several roller applicators in a
reservoir containing the coating composition of Example I. After
the coating composition is applied, the strands are then passed
through a forced air oven to cure the coated glass fiber strand.
The cured coated glass fiber strand having a 30 percent weight
gain, based upon the weight of the dry glass, of the sizing and
coating composition is impregnated with standard rubber stock and
tested for adhesion in accordance with the methods employed in
Example I. The rubber articles tested in this manner have adhesions
ranging between 36 and 50 pounds.
Similar results may be obtained when other polycarboxylic
acid-polyamine, anhydride-polyamine, or polyanhydride-polyamine
reaction products are used in lieu of the maleic
anhydride-tetraethylene pentamine reaction product of Examples I
and II. Also these compositions may be used as a combined sizing
and coating composition in accordance with the procedures described
in U.S. Pat. No. 3,718,449.
While the invention has been described with respect to details of a
preferred coating composition, other formulations of the coating
composition and the combined coating and sizing composition are
contemplated and should be obvious in light of the specification.
It is thus to be understood that the invention is not necessarily
limited to the precise formulations and methods described herein
except insofar as is set forth in the accompanying claims.
* * * * *